add --listen-open flag for web LAN binding

DEVLOG.md

@@ -96,3 +96,13 @@
 - Reused Rust simulation engine and instance lifecycle for backend execution.
 - Rebuilt `index.html` and `data.js` as a modern web dashboard UI backed by Rust APIs.
 - Removed legacy client-side simulation engine from the browser path.
+
+## 2026-02-11 - Open listen option for web mode
+
+### Scope completed
+- Added `--listen-open` CLI argument for web mode.
+- Enforced `--listen-open` usage only when `--web` is present.
+- Updated web server bind address behavior:
+  - default: `127.0.0.1:9009`
+  - open listen: `0.0.0.0:9009`
+- Updated startup logs and README usage examples for LAN-accessible mode.

README.md

@@ -81,9 +81,16 @@ Then open:
 http://127.0.0.1:9009
 ```
 
+Open web mode on all network interfaces (`0.0.0.0:9009`) so other machines can access it:
+
+```bash
+cargo run -- --web --listen-open
+```
+
 Notes:
 - The web frontend (`index.html` + `data.js`) now uses Rust backend APIs.
 - Simulation logic runs server-side in Rust (shared with CLI/TUI engine).
+- `--listen-open` is only valid with `--web` and should be used on trusted networks.
 
 ### Quick match (headless)
 

src/main.rs

@@ -32,6 +32,9 @@ struct Cli {
     #[arg(long, global = true)]
     web: bool,
 
+    #[arg(long, global = true)]
+    listen_open: bool,
+
     #[command(subcommand)]
     command: Option<Commands>,
 }
@@ -76,6 +79,13 @@ fn main() -> io::Result<()> {
     let cli = Cli::parse();
     let base_seed = cli.seed.unwrap_or_else(|| Rng::from_time().next_u64());
 
+    if cli.listen_open && !cli.web {
+        return Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "--listen-open can only be used with --web",
+        ));
+    }
+
     if cli.web {
         if cli.command.is_some() {
             return Err(io::Error::new(
@@ -83,7 +93,7 @@ fn main() -> io::Result<()> {
                 "--web cannot be combined with subcommands",
             ));
         }
-        return run_web_server(base_seed, cli.speed);
+        return run_web_server(base_seed, cli.speed, cli.listen_open);
     }
 
     match cli.command {

src/web.rs

@@ -457,17 +457,28 @@ async fn api_export_csv(path: web::Path<usize>, state: web::Data<SharedState>) -
         .body(csv)
 }
 
-pub fn run_web_server(base_seed: u64, speed: Speed) -> io::Result<()> {
+pub fn run_web_server(base_seed: u64, speed: Speed, listen_open: bool) -> io::Result<()> {
     let shared = SharedState {
         inner: Arc::new(Mutex::new(WebState::new(base_seed, speed))),
     };
 
     let ticker = shared.clone();
+    let bind_host = if listen_open { "0.0.0.0" } else { "127.0.0.1" };
+    let display_host = if listen_open {
+        "<machine-ip>"
+    } else {
+        "127.0.0.1"
+    };
 
     println!(
-        "Starting SoccerCloud web UI at http://127.0.0.1:{WEB_PORT} (seed={base_seed}, speed={})",
+        "Starting SoccerCloud web UI at http://{display_host}:{WEB_PORT} (bound {bind_host}:{WEB_PORT}, seed={base_seed}, speed={})",
-        speed.label()
+        speed.label(),
     );
+    if listen_open {
+        println!(
+            "Open listen enabled: accessible from other machines on your network at http://<machine-ip>:{WEB_PORT}"
+        );
+    }
 
     actix_web::rt::System::new().block_on(async move {
         actix_web::rt::spawn(async move {
@@ -507,7 +518,7 @@ pub fn run_web_server(base_seed: u64, speed: Speed) -> io::Result<()> {
                         ),
                 )
         })
-        .bind(("127.0.0.1", WEB_PORT))?
+        .bind((bind_host, WEB_PORT))?
         .run()
         .await
     })